Hoth, et al. U.S. Provisional Application No. 60/842,319, filed Sep. 5, 2006, entitled Automatic Bore Size Control By Completely Integrating An Air Gage System Into The Machine Control, is incorporated herein by reference in its entirety.
A machine's control process can be improved utilizing information feedback from a gaging system that measures a machined feature immediately after the machine cycle is finished. This concept is particularly applicable to machining processes, such as honing a bore of a workpiece.
The information is used to compensate or offset the existing parameters that control the honing or other machining operation. This can be done for either in-processing or post-processing gaging.
In-process gaging involves determining or measuring machined parameters, during the machining cycle. In honing, in-process gaging is typically implemented by gaging the bore during the honing machine cycle, and may utilize a gage capability incorporated into the honing tool. Using this method, the machine monitors the actual gage measurement to know when to end the machine cycle. When honing in this mode, all aspects of the cycle, particularly pertaining to the feed system for the honing tool, are controlled by the gage reading. Presently, when utilizing a gage in this manner, there will be a time period, or latency, between when the measurement is made, and when the machine control can read the measurement, which latency is often undesirable, as it slows the honing process.
Post-process gaging typically involves measuring the bore or other machined feature after the machine cycle is complete. The gage control system will acquire the bore measurements and then process the data to determine whether or not compensation needs to be made. This information is then passed on to the machine control system which will typically make the necessary adjustments at the beginning of the next machine cycle.
Interfacing a Gage System to an Existing Machine
Typically, known machines utilizing either in-process or post-process gaging, would do so by means of a separate gaging system hardwired to an existing machine. The two controllers, one on the machine and the other on the gaging system, would communicate through some type of electrical devices, for example, discrete I/O lines or a serial bus. In some instances, the gaging system may even control various motors or other positional type devices to locate the gage in position for taking a measurement, e.g. positioning an air probe in a bore.
An advantage of having the gage system as a separate unit from the machine is that it can be incorporated into a machine after the machine has been built and is operational. The initial design of the machine does not necessarily have to take into account that it needs to interface to a gaging system.
A disadvantage of this type of machine/gage system is the latency, that is, the time it takes for data feedback from the gaging control system to the machine control system, and processing time. The information sent to the machine by an external gaging system would typically lag too much in time and could not be used to control an in-process gaging operation, or dynamically display the data. Another disadvantage would be the cost and time to implement the additional gaging system. This would be particularly true if the machine does not have an existing means to interface with the gage system. In addition to needing a method of communication between the two control systems, a physical hardware connection would be required for safety reasons. An example is the Emergency Stop circuitry presently used on all computer-controlled machines. When an Emergency Stop button is pressed, a fault condition exists, and all machine movement is immediately stopped. In some situations it is probable that various machined components will be controlled by one or both systems, so both systems must communicate when the other is in a fault condition so that all movement is stopped.
Additionally, when utilizing separate machine and gaging controls, there would be redundancies inherent to connecting two different control systems together. Since both systems would require power it is very feasible that each would have its own power source including the safety devices for the power circuits. Both systems would have their own display and controller. As a result, the operator would have to learn to operate two different systems.
All these things require time and money to design, and put into operation. Some air gaging integrations into machines can be quite complex involving numerous cables and connections. The more complex a system is, the more unreliable it becomes.
Thus, what is sought is in a capability of integrating a gaging system into a machine control, which provides one or more advantages of in-process and/or post-process gaging to a machining operation, particularly a honing operation, and which overcomes one or more of the disadvantages and shortcomings set forth above.